Koss SB45 are amazing for $20. I have them, and I compared them to my $105 AD700. While the AD700 won, the SB45 put up an amazingly good fight. They actually sounded almost exactly the same, save for somewhat worse highs on the SB45 and lack of airyness that the AD700 had.
If I was rational, I would've been perfectly happy with a $20 headset that sounded probably 70-80% like a headphone 500% its cost. But noooooo, those audiophile bastards just kept making me want to go higher and maybe hear a smidgeon of what they hear with their $2000 setups -_-
Speaking of which, I'm now considering a $450 ALO HFI-780 to replace the AD700's I got nary a month ago. Damn audiophiles and their nice sounding adjectives
In summary, SB45 = BEST gaming headphones in terms of Price/Performance, bar none. Koss KSC75 would probably equal them, but they don't have a mic